Ultra high frequency space resonant system



1947', E. D. M ARTHLJR ULTRA HIGH FREQUENCY SPACE RESONANT SYSTEMS Filed March 20 1943 2 Sheets-Sheet 1 Fig.2.

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In v e n t o r Q, m A r C 0 i cA n .m e H m 5 v June 3, 1947. E. D. MCARTHUR 2,421,635

ULTRA HIGH FREQUENCYSPACE RESONANT SYSTEMS Filed March 20, 1945 2 Sheets-Sheet 2 Fig.4. Fig.5. /z /4 I His Attofnegm Patented June 3, 1.947

ULTRA HIGH FREQUENCY SPACE RESONANT SYSTEM Elmer D. McArthur, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application March 20, 1943, Serial No. 479,924

8 Claims.

My invention relates to ultra high frequency systems and more particularly to ultra high frequency space resonant, systems employing electric discharge devices.

The subject matter of the present invention is an improvement in systems of the general character disclosed and claimed in U. S. Letters Patent No. 2,284,405, granted May 26, 1942, upon my application, and which is assigned to the assignee of the present application.

In the use of ultra high frequency space resonant systems which employ as an element, or elements, thereof electric discharge devices, it is frequently desirable to provide means for controlling a net or resultant electrical characteristic of the space resonant systems as a whole, or to provide controllable coupling means between the space resonant regions to obtain the desired flexibility of operation. In accordance with the teachings of my invention described hereinafter, I provide new and improved control means for space resonant oscillators.

It is an object of my invention to provide a new and improved ultra high frequency space resonant system.

It is another object of my invention to provide a new and improved ultra high frequency oscillator and control means therefor.

It is a, further object of my invention to provide new and improved coupling means between cavities of a space resonant system.

It is a still further object of my invention to provide tuning means for a space resonant system employing an electric discharge device wherein the tuning means is positioned with respect to an electromagnetic wave or standing electromagnetic wave to produce an electrical effect thereof which is equivalent to an inter-electrode capacitance of the discharge device.

Briefly stated, in the illustrated embodiment of my invention I provide aspace resonant high frequency system, such as a space resonant oscillator, com-prising a plurality or pair of space resonant cavities which may be defined by three substantially parallel alined disks of conductive character and which are provided with a suitable input and output electrode means so that energy may be delivered to and derived fro-m the system. Associated with the space resonant cavities, I provide an electric discharge device, or a plurality of properly positioned electric discharge devices each having electrodes such as an anode, a cathode and a grid, respectively, connected to the disks so that the grid-cathode circuit of each discharge device may be energized in response to the electrical variations within one of the cavities, and so that the anode-grid circuit may be employed to deliver energy to the other cavity, thereby serving to produce amplified oscillations and maintain the system in oscillation.

The electric discharge device or devices are preferably positioned within the cavities at points corresponding to anti-nodes of the standing potential Wave incident to the resonant character of the cavities, and the discharge devices may be generally considered as being positioned at points suitable for driving the space resonant system. I also provide at properly positioned points in one of the cavities tuning means so located with respect to a standing electromagnetic wave, such as a potential standing wave, to couple the pair of cavities through the electric discharge device. Stated in other words, the tuning means is positioned within the cavity at a point, or points, so that the net or resultant electrical effect thereof is equivalent to an interelectrode capacitance of the discharge device or devices. For example, I may employ capacitive tuning means located physically apart from the discharge device, or devices, and which are located at points corresponding to the maximum value of the standing potential wave of the electromagnetic wave within the cavity. By controlling the effective area of the capacitive tuning means, which may constitute an adjustable plate extending into one of the cavities, the net or resultant inter-electrode capacity of an associated discharge device is controlled, thereby controlling the natural frequency of the input cavity.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. Fig. 1 of the drawings is a cross-sectional view of one modification of my invention wherein the space resonant cavities are defined by three alined disks and in which the system comprises a pair of electric discharge devices of peculiar form wherein the terminal plates supporting the electrodes facilitate connection to the disks. Fig. 2 is an enlarged cross-sectional view of one of the discharge devices, and Fig. 3 is a detailed cross-sectional view of the cathode construction for such discharge devices. Fig. 4 is another cross-sectional view of the system shown in Fig. 1 and shows a pair of tuning means positioned along a diametric axis in quadrature to thel axis of the electric discharge devices shown in Fig. 1. Fig. 5 is a plan view of the space resonant system showing the relative positions of 3 the electric disch'arge devices and the tuning means.

Referring now to Fig. 1, my invention is there illustrated as applied to an ultra high frequency space resonant system, such as an ultra high frequency oscillator, comprising pair of, space resonant cavities l and 2 which may be defined by conductive members such as metallic disks 3, 4 and 5 which are preferably substantially parallel and which are provided with centrally alined apertures to receive concentric transmission lines :to be described presently. In such an arrangement, disks 3 and 4 may be employed .as the input system defining an input cavity which is supplied with an exciting signal through a coaxial transmission line comprising an outer tubular conductor 6 and an inner conductor 1-, the outer tubular conductor being electrically insulated from disk 3, so far as unidirectional potentials are concerned, by means of an annular insulating spacer 8. 'Disks 4 and 5 in such a system may comprise or define the output cavity which is coupled to a, second transmission line comprising an outer tubularconductor 9 and an inner conductor It), the outer conductor 9 being insulated from disk 5,,so far as unidirectional potentials are concerned, by means of an annular spacer ll. The connection or shunting of the disks 3, t and 5 may be accomplished by overlapping flanges i2 and {3 associated with one pair of disks, and flanges Hi and associated with the other pair of disks. These flanges are separated by insulator l6 and H to prevent short circuit of the direct current components of the system. However, .due to the mutual capacitance thereof, these elements are effective as coupling means so far as the high frequency components of voltageof the system are concerned. Provision of suchoverlapping flanges serves to prevent appreciable external radiation of wave energy withincavities I and 1 without thereby effecting in any objectionable way the desirable resonant characteristics or qualities of the system.

In order to establish within the input space resonant cavity l electromagnetic oscillations, I provide an, input electrode means comprising a loop of WireIS electrically connected to disk t and conductor l of the input transmission line, and '-this wire extends through an aperture in the outer tubular conductor 6. In like manner, I provide a coupling or output electrode mean between the output cavity 2 and the output concentric transmission line comprising conductors 9 and IB, and which may comprise a loop of wire l9 electrically connected to disk and the inner conductor I0 extending through an aperture in outer conductor 9.

V I Provide in association with the space resonant cavities; l and 2 a plurality of properly positioned amplifying electric discharge devices, such as a pair of diametrically disposed electric discharge devices and 2!. These discharge devices are preferably positioned radially from the center line of the disks at positions within the vicinity of the potential maximum or an anti-node of the standing potential Wave of the electromagnetic energization within the space resonant regions or cavities I' and 2.

The positions of the electric discharge devices 20 and 2] relative to the dimensions of the disks defining the space responant cavities, and more specifically theradii of disks 3, 4 and 5 and the radii of thetubular conductors 6 and 9, or the diameters of the central apertures of these disks,

are fully set forth in the above-mentioned Patent No. 2,284,405 and reference is here made to the disclosure of that patent for the optimum positioning of such discharge devices. Generally speaking, it may be stated that the discharge devices 25 and 2| are positioned symmetrically in order to facilitate parallel operation of the devices, and maximum utilization of the electromagnetic wave energy is obtained by positioning the devices Within the vicinity of the potential maximum of the standing wave.

Each of the discharge devices 20 and 2|, as shown in enlarged View in Fig. 2, comprise a series of three disk-like members 22, 23 and 2 3 which are insulated and spaced by glass cylinders 25 and 26 which are hermetically joined at their extremities to disks 22-24, respectively. The metal disks 22-24 may be constructed of an alloy of nickel, iron and cobalt coated with copper to facilitate the sealing operation.

Disk 22 i provided centrally with a cathode comprising a hollow cylinder 21 having its extremity closed by a metal "cap 28 which is coated on its outer surface with an electron emissive material. Disk 28 is maintained'at an electron emissive temperature by means of a heating element 29 shown in Fig. '3 and which is supplied with heating current by means of lead-in conductors 3E) and 3! sealed into'an outwardly extending cylinder 32 which i provided with a glass seal 33 supporting conductors 30 and 3!. A metal heat shield 34 is provided in proximity to the cathode heating element 29.

At the other end of each electric discharge device, referring again to Fig. 2, there is provided within the central area of disk 24 a solid metal cylinder 35 which constitutes an anode element of the discharge device. Interposed between the cathode cylinder 21 and the anode 35 there is provided a spaced grid 36 supported by disk 23.

The disks 2224 of each discharge device'constitute substantially continuous surfaces with respect to disks 3, 4 and 5; thereby providing a highly satisfactory arrangement'for the coupling of the electrodes of the device to the space resonant cavities. Disk 24 may beifitted into an annular or cylindrical opening 31 in the inner surface of disk 5 to present a substantially continuous and smooth electrical connection, and disks 22 and 23 may be connected to disks 3 and 4 by means of a' plurality of annularly spaced or resilient conductive members 38 and 39.

In Fig. 4 there is illustrated another cross-sectional view of the space resonant system shown in Fig. 1 in geometric or physical quadrature with respect to that 'shoWn'in Fig.1 and which is drawn to a slightly different scale; Elements shown in Fig. 4 have been assigned reference numerals correspondingto the elements shown in Fig.1.

In order to control the resonantfrequency'of the space resonant cavity I, I provide 'a'tuning or coupling element,"'or a plurality of, tuning'or coupling elements, such as capacitance tuning means 4|] and ti, which comprise plates 42 and 33 having an appreciable surface area transverse to the radial direction within the cavity I. The tuning means 49 and 4! are positioned with respect to a standing wave within the cavity. I to produce an electricaleffect'equivalent to an inter-electrode capacitance, of discharge devices 2i} and 2!; For example, the positioningofan electr ostatictuningmeans within the vicinity of a potential maximum of the standing electromagnetic wave will 'exert'fan electrical effect equivalent to the grid cathode capacitance of the discharge devices. Each of the tuning. means 40 and 4| may comprise a tubular member 44 adapted to receive ascrew-thread extension 45 which supports the' associated tuning plate and is providedwith an externally accessible head 46 to permit adjustment of the'position of the plate within the cavity. As a. means for preventing the dissipation of electromagnetic energy through the small space between the screw threads and tubular member 44, I provide a shielding means which may comprise a metallic or conductive nut 41 in close engagement with the outer end of member 44.

In Fig. 5 I have illustrated a plan View of. the disk type space resonant oscillator described above wherein the relative positions of the electric discharge devices 2i] and 2| and the tuning means 40 and 4! are shown. It will be noted that the discharge devices 28 and 2! and tuning means 40 and 4| lie upon a circle and are consequently equidistant from the center line of the disks 3, 4 and 5, preferably located at a radial distance corresponding to a potential maximum of the standing wave. While in the particular embodiment of my invention described above. the electric discharge devices are shown as being two in number and as being located in a diametric axis in space quadrature with respect to the axis of tuning means 40 and 4!, it will be appreciated that within the purview of my invention this particular geometry and spacing of the elements is not a limitation. For example, a larger number of electric discharge devices may be employed, the radial positions of which and the relative positions of the tuning means will be determined by the geometry of the space resonant oscillator and the mode of oscillation of that oscillator, One of the important aspects is the provision of a tuning means which may be either inductive or capacitive which is properly correlated with respects to a standing current or potential wave to exert a resultant electrical effect on an interelectrode capacitance of the discharge devices.

In operation, upon the impression of a suitable high frequency signal voltage between conductors B and I of the input transmission line there will be established within the input cavity l associated with the grid-cathode circuits of discharge devices 2e and 2! electrical oscillations of a frequency determined by the input excitation. Electric discharge devices 25% and 2! serve as amplifiers to produce within the output cavity 2 amplified electromagnetic oscillations which may be utilized in an external circuit connected to the output transmission line comprising conductors 9 and II].

The control of the magnitude of the coupling between cavities l and 2 through the inter-electrode capacitances of the discharge devices 20 and 2| is obtained by positioning the plates 42 and 43 of tuning means 46 and 4|. As plates 42 and 43 thereof are extended greater distances into the cavity I, thereby affording greater surfaces transverse to the direction of energy fiow radially within said cavity, the capacitive effect thereof is increased. This effect is equivalent to an increase in the grid-cathode and the gridplate capacitances of discharge devices 29 and 21.

While I have shown and described my invention as applied to a space resonant system of particular configuration and as showing various devices diagrammatically, it will be obvious to those skilled in the art that changes and modifi- 6 cations may be made without departing fromlny invention, and Itherefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention. I

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An ultra high frequency space resonant system comprising a cavity resonator definedby a substantially closed conductive memberhaving a plurality of predetermined points corresponding to an anti-node of a standing potential wave in said resonator at a desired operating frequency of said system, an electric discharge device positioned within said cavity resonator, said electric discharge device having electrodes each connected to one of said points of said member, and tuning means within said cavity resonator physically displaced from said electric discharge device but positioned at another of said points.

2. An ultra high frequency space resonant system comprising a cavity resonator defined by a substantially closedconductive member'lhaving a plurality of predetermined points corresponding to an anti-node of a standing potential wave in said resonator at a desired operating frequency of said system, an electric discharge device compris ing a plurality of electrodes including an anode, a cathode and a grid, the electrodes of said discharge device each being connected to one of said points on said member, and tuning means physically displaced from said discharge device but positioned within said cavity resonator at another of saidpoints.

3. An ultra high frequency space resonant system comprising a pair of cavity resonators defined by three substantially parallel conductive disks, an electric discharge device positioned within said cavity resonators and comprising an anode, a cathode, and a grid provided with externally accessible high frequency terminals which. are respectively connected to the outer of said disks and the intermediate one of said disks. said discharge device being positioned radially at a predetermined point corresponding to a potential antinode of the standing electro-magnetic waves within said cavity resonators at a predetermined operating frequency of said system and tuning meanswithin one of said cavityresonators physically displaced from said discharge device and positioned radially at a point corresponding to a potential anti-node of the standing potential wave within said one resonator. at said operating frequency.

4. An ultra high frequency space resonant system comprising a pair of cavity resonators defined by three substantially parallel conductive disks, a plurality of electric discharge devices positioned within said cavity resonators and located at radial predetermined points thereof corresponding to a potential anti-node of a standing potential wave therewithin at a predetermined operating frequency of the system for maintaining said resonators in oscillation at said frequency, each of said discharge devices comprising an anode, a cathode and a grid provided with externally accessible high frequency terminals which are respectively connected to the outer of said disks and the intermediate one of said disks, and tuning means within one of said cavity resonators physically displaced from said discharge devices and positioned at a radial predetermined point thereof corresponding to a potential antinode of the standing potential waves in said resonator at said operating frequency.

5. An ultra high frequency space resonant system comprising a pair of cavity resonators defined by' three substantially parallel conductive disks, a plurality of electric discharge devices positioned within said cavity resonators and located at predetermined radial points thereof corresponding to a potential anti-node of a standing potential wave therewithin at a predetermined operating frequency of said system for maintaining saidresonators in oscillation at said operating frequency, each of said discharge devices comprising an anode, a cathode and a grid provided with externally accessibl high frequency terminals which are respectively connected to the outer of said disks and the intermediate one of said disks, and a plurality of tuning means within one of said cavity resonators physically displaced from each other and from said discharge devices, said tuning means and said devices being symmetrically positioned within said one cavity resonator and said tuning means being positioned at predetermined radial points thereof corresponding to a potential antinode of a standing potential wave within said one resonator at said operating frequency.

6. An ultra high frequency space resonant system comprising a pair of cavity resonators defined by three substantially parallel conductive disks, a pair of electric discharge devices positioned diametrically within said cavity resonators and each comprising an anode, a cathode and a grid provided with externally accessible high frequency terminals which are respectively connected to the outer of said disks and the intermediate one of said disks, said discharge devices being positioned radially with respect to the axis of said disks at predetermined points corresponding to a potential anti-node of the standing electromagnetic Waves within said cavity resonators at a predetermined operating frequency, and a pair of tuning means within one of said cavity resonators spaced in quadrature with respect to said discharge devices at predetermined points corresponding to a potential anti-node of the standing electromagnetic waves with said cavity resonator at said operating frequency.

7. An ultra high frequency space resonant system comprising a pairof cavity resonators defined by three substantially parallel conductive disks, a pair of electric discharge devices positioned diametrically within said cavity resonators and each comprising an anode, a cathode and a grid provided with externally accessible high frequency terminals which are respectively connected to the outer of said disks and the intermediate one of said disks, said discharge devices being positioned radially with respect to the axis of said disks at predetermined points corresponding to a potential anti-node of the standing electro-magnetic waves within said cavity resonators at a predetermined operating frequency, and a pair of tuning means in'spaced quadrature with respect to the diametric position of said discharge devices at predetermined points corresponding to a potential anti-node of the standing electromagnetic waves within said cavity resonators at said operating frequency.

8. An ultra high frequency space resonant system comprising a pair of cavity resonators defined by three substantially parallel conductive disks, a pair of electric discharge devices positioned diametrically within said cavity resonators and each comprising an anode, a cathode and a grid provided with externally accessible high frequency terminals which are respectively connected to the outer of said disks and the intermediate one of said disks, said discharge devices being positioned radially with respect to the axis of said disks at predetermined points corresponding to a potential anti-node of the standing electromagnetic wave in said resonators at a predetermined operating frequency, and tuning means within one of said cavity resonators physically displaced from said discharge devices and positioned at predetermined points corresponding to a potential anti-node of the potential wave within said one resonator at said operating frequency.

ELMER D. MCARTHUR.

REFERENGES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

